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/*
    This file is part of cpp-ethereum.

    cpp-ethereum is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    cpp-ethereum is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file CodeFragment.h
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#pragma once

#include <iostream>
#include <sstream>
#include <libethential/Common.h>
#include <libevmface/Instruction.h>
#include "Exceptions.h"

namespace dev
{
namespace eth
{

enum AssemblyItemType { UndefinedItem, Operation, Push, PushString, PushTag, PushSub, PushSubSize, Tag, PushData };

class Assembly;

class AssemblyItem
{
    friend class Assembly;

public:
    AssemblyItem(u256 _push): m_type(Push), m_data(_push) {}
    AssemblyItem(Instruction _i): m_type(Operation), m_data((byte)_i) {}
    AssemblyItem(AssemblyItemType _type, u256 _data = 0): m_type(_type), m_data(_data) {}

    AssemblyItem tag() const { assert(m_type == PushTag || m_type == Tag); return AssemblyItem(Tag, m_data); }
    AssemblyItem pushTag() const { assert(m_type == PushTag || m_type == Tag); return AssemblyItem(PushTag, m_data); }

    AssemblyItemType type() const { return m_type; }
    u256 data() const { return m_data; }

    int deposit() const;

    bool match(AssemblyItem const& _i) const { return _i.m_type == UndefinedItem || (m_type == _i.m_type && (m_type != Operation || m_data == _i.m_data)); }

private:
    AssemblyItemType m_type;
    u256 m_data;
};

typedef std::vector<AssemblyItem> AssemblyItems;
typedef vector_ref<AssemblyItem const> AssemblyItemsConstRef;

std::ostream& operator<<(std::ostream& _out, AssemblyItemsConstRef _i);
inline std::ostream& operator<<(std::ostream& _out, AssemblyItems const& _i) { return operator<<(_out, AssemblyItemsConstRef(&_i)); }

class Assembly
{
public:
    AssemblyItem newTag() { return AssemblyItem(Tag, m_usedTags++); }
    AssemblyItem newPushTag() { return AssemblyItem(PushTag, m_usedTags++); }
    AssemblyItem newData(bytes const& _data) { h256 h = (u256)std::hash<std::string>()(asString(_data)); m_data[h] = _data; return AssemblyItem(PushData, h); }
    AssemblyItem newSub(Assembly const& _sub) { h256 h = h256::random(s_fixedHashEngine); m_subs[h] = _sub; return AssemblyItem(PushSub, h); }
    AssemblyItem newPushString(std::string const& _data) { h256 h = (u256)std::hash<std::string>()(_data); m_strings[h] = _data; return AssemblyItem(PushString, h); }
    AssemblyItem newPushSubSize(h256 const& _subId) { return AssemblyItem(PushSubSize, _subId); }

    AssemblyItem append() { return append(newTag()); }
    void append(Assembly const& _a);
    void append(Assembly const& _a, int _deposit);
    AssemblyItem const& append(AssemblyItem const& _i);
    AssemblyItem const& append(std::string const& _data) { return append(newPushString(_data)); }
    AssemblyItem const& append(bytes const& _data) { return append(newData(_data)); }
    AssemblyItem appendSubSize(Assembly const& _a) { auto ret = newSub(_a); append(newPushSubSize(ret.data())); return ret; }

    AssemblyItem appendJump() { auto ret = append(newPushTag()); append(Instruction::JUMP); return ret; }
    AssemblyItem appendJumpI() { auto ret = append(newPushTag()); append(Instruction::JUMPI); return ret; }
    AssemblyItem appendJump(AssemblyItem const& _tag) { auto ret = append(_tag.pushTag()); append(Instruction::JUMP); return ret; }
    AssemblyItem appendJumpI(AssemblyItem const& _tag) { auto ret = append(_tag.pushTag()); append(Instruction::JUMPI); return ret; }

    template <class T> Assembly& operator<<(T const& _d) { append(_d); return *this; }

    AssemblyItem const& back() { return m_items.back(); }
    std::string backString() const { return m_items.size() && m_items.back().m_type == PushString ? m_strings.at((h256)m_items.back().m_data) : std::string(); }

    void onePath() { assert(!m_totalDeposit && !m_baseDeposit); m_baseDeposit = m_deposit; m_totalDeposit = INT_MAX; }
    void otherPath() { donePath(); m_totalDeposit = m_deposit; m_deposit = m_baseDeposit; }
    void donePaths() { donePath(); m_totalDeposit = m_baseDeposit = 0; }
    void ignored() { m_baseDeposit = m_deposit; }
    void endIgnored() { m_deposit = m_baseDeposit; m_baseDeposit = 0; }

    void popTo(int _deposit) { while (m_deposit > _deposit) append(Instruction::POP); }

    void injectStart(AssemblyItem const& _i);

    std::string out() const { std::stringstream ret; streamOut(ret); return ret.str(); }
    int deposit() const { return m_deposit; }
    bytes assemble() const;
    Assembly& optimise(bool _enable);
    std::ostream& streamOut(std::ostream& _out, std::string const& _prefix = "") const;

private:
    void donePath() { if (m_totalDeposit != INT_MAX && m_totalDeposit != m_deposit) throw InvalidDeposit(); }
    unsigned bytesRequired() const;

    unsigned m_usedTags = 0;
    AssemblyItems m_items;
    mutable std::map<h256, bytes> m_data;
    std::map<h256, Assembly> m_subs;
    std::map<h256, std::string> m_strings;

    int m_deposit = 0;
    int m_baseDeposit = 0;
    int m_totalDeposit = 0;
};

inline std::ostream& operator<<(std::ostream& _out, Assembly const& _a)
{
    _a.streamOut(_out);
    return _out;
}

}
}